The invention relates to cigarette-type filtered smoking articles and to tipping papers therefor.
In the past 30 years, cigarettes have evolved towards lower tar and nicotine. Initially, the unfiltered cigarette was modified by adding relatively short filters composed of synthetic fibers, typically cellulose acetate, to aid in the removal of particulate matter from mainstream smoke. Later, further reductions in particulate and nicotine yields became desirable. This end was accomplished by increasing length and efficiency of the filters used and by incorporation of moderate to high levels of ventilation in the filter systems of low tar delivery cigarettes. The use of high efficiency filters and filter ventilation reduced the total yield of nicotine and particulate matter on a per cigarette basis as well as the yields of individual cigarette puffs. Thus, conventional low tar cigarettes have not only a reduced strength, but also have reduced taste properties relative to their higher delivery counterparts.
Various cigarette modifications have been proposed to reduce tar and nicotine delivery. For example, U.S. Pat. No. 2,836,183, to Fay et al discloses filtered smoking articles including a warning indicia operatively associated with a point on the tobacco rod at about its midpoint. This warning indicia is intended to encourage the smoker to discontinue smoking the cigarette past about the midpoint of the tobacco rod.
U.S. Pat. No. 3,368,566 discloses a filtered cigarette having a composite filter which includes a plurality of short filters which mechanically and chemically remove and alter various components of cigarette smoke. The series of short filters may be replaced by a single filter having a plurality of zones bearing some sequential resemblance to the mechanical and chemical acting short filter elements.
U.S. Pat. No. 3,913,590 to Sway discloses a multi-sectioned cigarette including a tobacco rod segment at the lighting end of the cigarette which generally comprises from about one-half to about two-thirds of the entire length of the cigarette. Adjacent the tobacco rod is an inert, non-combustible, porous and generally inorganic element capable of extinguishing the fire cone of the cigarette. Downstream of the inert element, there is a second tobacco filler intended to add flavor to the filtered smoke from the burning end of the cigarette.
U.S. Pat. No. 4,570,650 to Sirota discloses a self-extinguishing cigarette comprising a tubular coating around the periphery of the part of the tobacco rod located closest to the filter of the cigarette. The burning tobacco self-extinguishes upon reaching the tubular coating. Additionally, the coating is intended to prevent a smoker from smoking the rear one-third to one-fourth of the tobacco rod.
Although some of the above proposals could potentially reduce the normal puff count of a conventional cigarette, they suffer from various drawbacks including cost, difficulty in manufacture, poor taste, unusual appearance and the like.
U.S. Pat. No. 4,146,040 to Cohn discloses a fire resistant cigarette including a coating on the cigarette paper which decreases burn rate of the tobacco rod. This patent proposes a cigarette with an elongated filter section and a shortened tobacco rod section wrapped with the coated paper. Because of the slower burn rate, the short tobacco rod can have the same amount of puffs as a conventional cigarette. As with the conventional low tar product, the taste and strength of the cigarette on an individual puff basis would be thereby reduced.
Additionally, certain commercially available ultra low tar, and yet lower tar, products having normal filter and tobacco rod lengths, exhibit lower than normal puff counts, of 6 to 6.5 due to tobacco blends having large amounts, greater than 50%, of puffed tobacco with or without cigarette papers of increased porosity. Because of the large amounts of puffed tobacco and/or paper modifications, such products have taste properties different from the full flavor tobacco blend.